8 to 22% of patients with common variable immunodeficiency (CVID) will develop Granulomatous Lymphocytic Interstitial Lung Disease (GLILD), which has emerged as a major cause of mortality. Little is known about GLILD in children and young adults. The aim of this study was to describe the clinical, functional, radiological and pathological features of children and young adults diagnosed with GLILD.

Variable common immunodeficiency (VCID) encompasses a heterogeneous group of primitive immunodeficiencies, with variable clinical and immunological settings, but globally characterized by hypogammaglobulinemia with significant reduction of Immunoglobulin G levels, often associated with a decrease in Immunoglobulin A and/or Immunoglobulin M levels, coupled with inability to produce antibodies in response to infection and/or immunization. VCID is the most common primary immunodeficiency, with an estimated prevalence between 1/10,000 and 1/50,000. With the introduction of high-dose, intravenous or subcutaneous immunoglobulins, number of infections, along with morbidity and induced mortality, has declined sharply in recent years. Conversely, non-infectious complications, such as autoimmune manifestations, inflammatory bowel diseases, enteropathies, hepatitis, lung disease and lymphoproliferation (up to lymphoma), increased considerably, reaching 70% of patients.

Granulomatous Lymphocytic Interstitial Lung Disease is a non-infectious complication that can occur during the evolution of VCID and which is usually the pulmonary manifestation of a systemic polyclonal lymphoproliferative disease. GLILD contained both granulomatous and lymphoproliferative histopathologic patterns such as lymphocytic interstitial pneumonia , follicular bronchiolitis, and lymphoid hyperplasia. In recent series, approximately 8 to 22% of patients develop GLILD in VCID, and this complication is associated with increased mortality.

Although there are now more studies conducted in the adult population, those in the pediatric population are only currently case report. To the best of our knowledge, very little data is available on this specific lung disease in the pediatric and young adults population.

Inclusion Criteria:

• patient aged to 0 to 25 years old (at the diagnosis of GLILD)
• diagnosed with a primary immunodeficiency syndrome "Common Variable Immunodeficiency" like, according to the 1999 American and European Societies for Immunodeficiency criteria
• Suspected with GLILD (Granulomatous Lymphocytic Interstitial Lung Disease

Exclusion Criteria:

• pulmonary diseases caused by other causes such as infectious or hypersensitivity pneumonitis

• Children and young adults, aged from 0 to 25 years-old
• with a diagnosis of Common Variable Immunodeficiency (marked decrease in IgG, at least less than -2 SD compared to the mean for age; associated with a decrease of at least one of the Immunoglobulin M or Immunoglobulin A isotypes, , absence of iso-haemagglutinins and/or poor vaccine response, with other defined causes of hypogammaglobulinemia excluded)
• GLILD suspected according to the lung biopsy or CT chest